Motor vehicles, as presently manufactured, are equipped for defogging and deicing windshields. Generally, these systems depend upon heat generated in the internal combustion engine of the vehicle and transferred to the engine's cooling system to be blown as warm air across the interior of the windshield to accomplish the defogging and deicing thereof. In such a case, of course, it is readily apparent that there is a period of time between the starting of an engine of a vehicle and the time that sufficient heat is being generated in its cooling system in order to provide a defogging and deicing of the vehicle's windshield. Depending upon the exact temperature conditions and the time the vehicle has been sitting idle without its engine running, the period of time before sufficient heat is available to accomplish this defogging and deicing function can be up to 10 minutes or more.
Ford Motor Company has recently introduced an electrically heated windshield in which heat is generated from electrical energy to accomplish a relatively rapid defrost and deicing of the vehicle's windshield. The electrically heated windshield is independent of the normal heating and defrosting system contained in the motor vehicle. The system is one which has an electrically conductive coating placed on the windshield prior to lamination of the two glass templets to form the windshield.
The specific method presently employed by Ford Motor Company in manufacturing its electrically heated windshields is set forth in U.S. patent application Ser. No. 823,233, filed Jan. 28, 1986, entitled "Method For Making An Electrically Heatable Windshield." This application has matured into U.S. Pat. No. 4,654,067. The specification of that application is hereby incorporated by reference.
The mentioned application teaches a process in which the two glass templets which are to form the windshield are bent into their curved configurations prior to placement of the conductive coating on one of the glass templets. The coating of the glass templets takes place at a relatively slow speed because intricate magnetron sputtering equipment needed to be designed to place a thin conductive coating on a curved glass sheet. The present equipment used by Ford Motor Company is one in which approximately one curved part may be coated per minute.
One way of improving the productivity of the process would be to coat the glass templets when they were in a flat conditions. In a flat condition, approximately seven parts per minute may be coated, which would mean an increase of six parts per minute. The problem, however, is that no one knew how to bend a coated glass template from its flat condition to a curved condition without oxidizing the conductive layer, thereby ruining it from an electrical standpoint.
No search was conducted on the subject matter of this specification in the U.S. Patent and Trademark Office or in any other search facility. The only prior art that I am aware of is that which has been discussed above.
It is a principal object of this invention to provide a method of manufacturing a curved windshield in which the glass bracket having the electrically conductive coating thereon is bent after the coating has been applied.